1. Field of the Invention
The present invention relates to a semiconductor device and a method for manufacturing the same.
2. Description of the Related Art
In recent years, in a solid-state imaging device which is one type of semiconductor device, in order to increase the amount of light incident on a photoelectric conversion portion, a solid-state imaging device having an optical waveguide has been proposed.
Japanese Patent Laid-Open No. 2009-272568 has disclosed a solid-state imaging device having an etch stop film used for forming a waveguide. In addition, Japanese Patent Laid-Open No. 2009-272568 has also disclosed the structure in which a high-refractive-index member forming a waveguide is provided on a pad portion. The present inventors found out the following problems. According to the structure of the solid-state imaging device describe in Japanese Patent Laid-Open No. 2009-272568, a step is unfavorably formed between an imaging region and a peripheral region. Since irregularity in thickness of an insulating layer is generated by the step, for example, irregularity in image and irregularity in color are generated in the imaging region. In addition, it is difficult to form a structural body, such as an on-chip color filter or an on-chip microlens, on a layer having a step with a high precision. In addition, also in semiconductor devices other than solid-state imaging device, the height of the device is increased concomitant with an increase in degree of integration, and as a result, there has been a problem in that the planarization cannot be easily performed in a manufacturing process.
As described above, according to Japanese Patent Laid-Open No. 2009-272568, it has been difficult to provide a semiconductor device having a high precision and to form a semiconductor device with a high precision. In consideration of the above problems, the present inventors provide a method for manufacturing a semiconductor device which can easily perform planarization and a semiconductor device in which planarization is performed.